Crayfishes of the virilis Section of Genus Orconectes

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New and Little-known

Crayfishes of the virilis Section of Genus Orconectes

(Decapoda: Cambaridae) from the Southeastern United States

MARTHA R. COOPER and

HORTON H. HOBBS, JR.

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY • NUMBER 320

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S M I T H S O N I A N C O N T R I B U T I O N S T O Z O O L O G Y • N U M B E R 3 2 0

New and Little-known Crayfishes of the virilis Section of Genus

Orconectes (Decapoda: Cambaridae) from the Southeastern United States

Martha R. Cooper and Horton H. Hobbs, Jr.

SMITHSONIAN INSTITUTION PRESS City of Washington

1980

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Cooper, Martha R., and Horton H. Hobbs, Jr. New and Little-known Crayfishes of the virilis Section of Genus Orconectes (Decapoda: Cambaridae) from the Southeastern United States. Smithsonian Contributions to Zoology, number 320, 44 pages, 13 figures, 6 tables, 1980.—Descriptions, illustrations, and all available information concerning the following previously known species are presented: Orconectes alabamensis (Faxon, 1884), 0. mississippiensis (Faxon,

1884), and 0. validus (Faxon, 1914). Similar treatments are accorded three new species: 0. cooperi from the Flint River basin in Alabama and Tennessee, 0. holti from the Alabama River watershed in Alabama, and 0. chickasawae from the Tombigbee drainage system in Mississippi.

OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Smithsonian Year. SERIES COVER DESIGN: The coral Montastrea cavemosa (Linnaeus).

Library of Congress Cataloging in Publication Data Cooper, Martha R

New and little-known crayfishes of the virilis section of genus Orconectes (Decapoda: Cambaridae) from the Southeastern United States.

(Smithsonian contributions to zoology ; no. 320) Bibliography: p.

Supt. of Docs, no.: SI 1.27:320

1. Orconectes—Classification. 2. Crustacea—Classification. 3. Crustacea—Southern States

—Classification. I. Hobbs, Horton Holcombe, Jr., 1914, joint author. II. Title.

III. Series: Smithsonian Institution. Smithsonian contributions to zoology ; no. 320.

QL1.S54 no. 320 [QL444.M33] 591s [595.3'841] 80-607029

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New and Little-known Crayfishes of the virilis Section of Genus

Orconectes (Decapoda: Cambaridae) from the Southeastern United States

Martha R. Cooper and Horton H. Hobbs, Jr.

Introduction

Prompted in part by a need to know the com- ponents of the crayfish fauna in the area of the proposed Tennessee-Tombigbee Waterway in western Alabama and northeastern Mississippi, several years ago we initiated a joint study of the genus Orconectes in the westward-flowing segment of the Tennessee River basin and in the Mobile River watershed. The members of the virilis section have been particularly in need of clarification. This report provides redescriptions, illustrations, discussions of range and variation, notes on the life history and ecology, and a list of crayfish associates for three previously known

species: Orconectes alabamensis (Faxon, 1884), 0.

validus (Faxon, 1914) and 0. mississippiensis

(Faxon, 1884). In addition, three species are described as new: one restricted to the Flint River watershed (Tennessee River basin) in Alabama and Tennessee, one from tributaries of the Ala- bama River in Alabama, and the third from the Tombigbee drainage system in Mississippi. Ad- ditional reports are planned as first form males

Martha R. Cooper, North Carolina State Museum of Natural History, P.O. Box 27647, Raleigh, North Carolina 27611. Horton H. Hobbs, Jr., Department of Invertebrate Zoology, National Museum of Natural

History, Smithsonian Institution, Washington, D.C. 20560.

become available from many localities which are at this time inadequately represented in collections at hand.

Unfortunately, without first form males, we have been unable to identify specimens of the genus from many localities in the Mobile and Tennessee basins. Among those species that pos- sess a depressed, strongly costate chela in which the dactyl bears a serrate row of tubercles mesial ly and a distinct excision on the proximal half of the opposable surface, the nonsecondary sexual characters may not always be reliable. Until the limits of variation of these characters in each of the species have been determined, a knowledge of the structure of the first pleopod of the first form male is indispensable.

As an illustration of the nature of the problem of identification of members of this complex, Hobbs (1972), in preparing a key to the North and Middle American crayfishes, found that the first pleopod of the syntypic male, form I, of

Orconectes mississippiensis had been broken, and he

chose a presumable topotypic specimen to illus- trate the species (p. 80, fig. 63a). The two specimens appeared to be so markedly similar (except that the areola of the supposed topotype was 1

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linear instead of being obliterated along part of its length) that he failed to note the relative lengths of the central projection of the first pleopods in them. He thus depicted the pleopod of one of the new species described herein instead of that of a specimen of 0. mississippiensis. Actually, the first pleopod of the first form male of the latter species (Figure llb,d,fji) is easily distin- guishable from that of the new species (Figure 10 b,f); however, those of the second form male are virtually identical (cf. Figures llc,g and lQc,e). Obviously, the first pleopod of the first form male must be available in order to deter- mine whether the specimens in question are grouped with those species having pleopods with long rami, as in 0. etnieri Bouchard and Bouchard (1976:459) and 0. mississippiensis, or with those possessing short ones, as in 0. immunis (Hagen,

1870:71) and two of the new species described herein (Figures 8 and 10).

Reference is made in the text to "adult males"

which are considered by us to include those males in the first form or second form males that have experienced at least one previous molt to first form. The measurement of the "total" or "mesial"

length of the first pleopod follows that of Fitzpa- trick (1967: fig. 1/), and constitutes the straight- line distance between the levels of the proxi- momesial and distal extremities of the pleopod (Figure 5j, ml). The annuli ventrales are described as being firmly, but not inflexibly, fused to the sternum; the sense of this is explained as follows. The annulus ventralis of certain crayfishes occurs as a sclerite surrounded by unscler- otized areas of the exoskeleton and is therefore freely movable. In other species, the annulus is joined to the sternum immediately anterior to it by a partially sclerotized membrane, thus "firmly fused" but slightly movable. In many, if not most, members of the genus OrconecUs, for example O.

erichsonianus (Faxon, 1898:659), the junction between the annulus and the sternum anterior to it is so heavily sclerotized that in respect to the sternum the annulus is "inflexibly fused" to it.

ACKNOWLEDGMENTS.—We are indebted to a number of persons for the specimens on which this report is based. Special thanks are extended

to Herbert T. Boschung and Thomas S. Jande- beur of the University of Alabama, Eugene C.

Beckham of Cornell University, Joseph F. Fitzpa- trick, Jr., of the University of South Alabama, and Harold Wahlquist of the Alabama Power Company for the large series of crayfishes donated to the Smithsonian Institution. We are also grateful to the following persons who assisted us in collecting other specimens: Glenn H. Clemmer of Mississippi State University; John E. Cooper of the North Carolina State Museum of Natural History; H. H. Hobbs III of Wittenberg Univer- sity; Kenneth R. Martin of Atlanta, Georgia;

James F. Payne of Memphis State University;

Daniel J. Peters of Yorktown, Virginia; Jean E.

Pugh of Christopher Newport College; John S.

Ramsey of Auburn University; Samuel R. Tel- ford of the University of Florida; and James D.

Williams, Office of Endangered Species, Fish and Wildlife Service, Washington, D.C. Thanks are also extended to Raymond W. Bouchard of the University of North Alabama both for lending specimens to us and for records of the occurrence in Tennessee of one of the new species described herein. Others whose assistance in obtaining specimens is appreciated are included under the several paragraphs devoted to "Specimens Exam- ined."

For their criticisms of the manuscript and/or aid in its preparation, we are grateful to John E.

Cooper and Joseph F. Fitzpatrick, Jr., and to Margaret A. Daniel and Raymond B. Manning of the Smithsonian Institution.

Orconectes alabamensis (Faxon)

FIGURES 1, 2a

Cambarus Alabamensis Faxon, 1884:124, 125-127, 146; 1885a:

85, 86, 102, 104-105, 161, 168, 174, 178, pi. IV: fig. 4; pi.

X: fig. 3, 3', 3a, 3a'; 1885b:359.—Underwood, 1886:366.

Cambarus alabamensis.—Hay, 1899:960, 962.—Ortmann, 1902:278; 1905:110, 112, 117, 127; 1931:90, 91-93.—

Stecle, 1902:7.—Harris, 1903:60, 70, 137, 146.—Faxon, 1914:383, 420.

Cambarus (Faxomus) alabamensis.—Ortmann, 1905:112.

Faxonius alabamensis.—Creaser, 1933a:3 [by implication];

1933b: 16; 1962:2 [by implication].

Faxonius {Faxonius) alabamensis.—Creaser, 1933b:21 [by im- plication].

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NUMBER 320

Orconectes alabamensis.—Hobbs, 1942a:352 [by implication];

1968:K12, K31, fig. 31h; 1972:89, 148, figs. 70f, 71d; 1974:

26, fig. 166.—Hart and Hart, 1974:75, 90.—Bouchard, 1976b: 14.—Fitzpatrick, 1976:56.—Hobbs and Walton, 1977:602.

Orconectes (Orconectes) alabamensis.—Hobbs, 1942b: 154 [by implication]; 1959:894.

DIAGNOSIS.—Body and eyes with pigment. Ros- trum with median carina and marginal tubercles present at base of acumen. Areola 3.6 to 6.4 times as long as wide and comprising 26.4 to 31.9 percent of entire length of carapace (34.7 to 41.1 percent of postorbital carapace length) with 4 to 7 punctations in narrowest part. Cervical spine small but well developed; suborbital angle vestigial; postorbital ridge well developed with small acute spines or tubercles cephalically. Antennal scale approximately 2.5 times as long as wide, broadest at or slightly distal to midlength. Chela with palm inflated, bearing row of about 7 squamous tubercles on mesial surface; fingers gaping, and mesial margin of dactyl with vestigial adpressed tubercles; opposable margin of dactyl not excised. Hook on ischium of third pereiopod of male. First pleopod of first form male without angular shoulder on cephalic surface, distal three- fifths inclined caudally, terminal elements with distal portions recurved and central projection reaching cephalic margin of coxa of second pleopod when abdomen flexed; pleopod length divisible into carapace length 2.7 to 3.0 (average 2.9) times; terminal elements slender, subparallel;

central projection constituting 30.6 to 33.5 (average 31.7) percent of total length of pleopod, bladelike, tapering to apex, and not extending so far caudally as mesial process; mesial process subcylindrical in section proximally, troughlike distally. Annulus ventralis as figured. First pleopod present in female.

SYNTYPIC MALE, FORM I.—Body and eyes pigmented. Cephalothorax (Figure la,*) subovate in section; abdomen narrower than carapace (10.9 and 11.6 mm), width of latter greater than depth in caudodorsal margin of cervical groove (11.6 and 10.2 mm). Areola broad, 4.4 times as long as wide, with 6 punctations across narrowest part, length 29.7 percent of entire length of carapace

(38.2 percent of postorbital carapace length).

Rostrum with margins not thickened, slightly elevated and gently converging to marginal tubercles; acumen reaching slightly beyond ultimate podomere of antennular peduncle; upper surface of rostrum with low carina cephalically, basal portion weakly excavate and thickly set with punctations. Subrostral ridge weakly developed, evident in dorsal aspect along basal half of rostrum. Postorbital ridge moderately strong, grooved dorsolaterally, and terminating cephalically in small tubercle. Suborbital angle vestigial, broadly rounded. Cervical spine small but well defined. Branchiostegal spine well developed.

Carapace densely punctate except cephaloventrally where punctations replaced by granula- tions. Abdomen longer than carapace (28.0 and 23.5 mm); pleura truncate ventrally, and with rounded caudoventral extremities; cephalic section of telson with 2 spines in each caudolateral corner. Proximal podomere of uropod with spine on each lobe, that on lateral one small; both rami with median keel, that on mesial ramus terminating in premarginal spine.

Cephalic lobe of epistome (Figure 1^), with prominent cephalodorsally directed cephalomedian projection, set off from main body of epistome by contracted base; cephalolateral margins rounded, slightly elevated; main body of epistome with prominent fovea; epistomal zygoma broadly arched. Basal segment of antennule with spine on ventral surface slightly distal to midlength. An- tennal peduncle with spine on lateral surface of basis and on ischium. Antenna reaching tergum of second abdominal segment. Antennal scale (Figure 1/) 2.5 times as long as broad, broadest at about midlength; mesial border of lamella evenly rounded except for weak hump distomesially;

apical spine slightly overreaching antennular peduncle. Ventral surface of ischium of third maxilliped clothed in plumose setae; distolateral angle of podomere acute.

Right chela (Figure \j) with palm inflated (ratio of depth to width 0.70), lacking lateral costa, shorter than carapace (18.5 and 23.5 mm), and 2.3 times as long as wide; thickness slightly more than two-thirds length of areola and little

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FIGURE 1.—Orcontctes alabamensis (syntypes, all from <JI except c, e, from 6*11, and d from $): a, lateral view of carapace; b, c, mesial view of first pleopod; d, annulus ventralis; e,f, lateral view of first pleopod; g, cpistome; h, basis and ischium of third pereiopod; t, dorsal view of carapace;

j , dorsal view of distal podomeres of cheliped; k, caudal view of first pleopods; /, antennal scale.

more than four-fifths length of mesial margin of palm, latter with 3 rows of small to vestigial tubercles: 8 in ventralmost, 7 in middle, and 6 in dorsal row (left chela with 5, 6, and 7, respec-

tively); remainder of chela punctate, lacking tu- bercles except on opposable margins of fingers.

Latter slightly gaping basally. Opposable surface of fixed finger with conspicuous tuft of plumose

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NUMBER 320

setae along basal half, denser ventrally than dorsally, margin with row of 9 tubercles along proximal two-thirds, and band of minute denticles extending from fifth tubercle to base of corneous tip of finger; dorsal and ventral surfaces with well-defined submedian longitudinal ridge flanked by setiferous punctations; setae on prox- imomesial side of ventral ridge contributing to setal tuft at base of finger; lateral margin of finger rounded with weak longitudinal ridge. Opposable margin of dactyl with row of 9 low rounded corneous tubercles along proximal two-thirds and band of minute denticles extending from fifth tubercle to corneous tip of finger; dorsal and ventral surfaces of finger with submedian longitudinal ridge; mesial surface with row of vestigial, strongly adpressed tubercles proximally giving way to setiferous punctations distally. Carpus 1.4 times as long as broad, with shallow groove dorsally, groove with angle at base of distal fourth;

dorsal and lateral surfaces punctate; mesial surface with prominent procurved spine and 2 large tubercles proximal to it; ventral surface punctate except for acute spine on lateral articular condyle.

Dorsal surface of merus with 2 premarginal tubercles one of which spiniform; lateral and mesial surfaces largely polished and sparsely punctate;

ventral surface with only 1 spiniform tubercle representing lateral row and 11 spiniform ones constituting mesial row; distolateral apophysis with spiniform tubercle. Ventromesial margin of ischium of cheliped with 1 tubercle.

Ischium of third pereiopod (Figure Ih) with simple hook overreaching basioischial articula- tion, not opposed by tubercle on basis. Ventral membrane on coxa of fifth pereiopod studded with short setae.

First pleopods (Figure \bjjc) symmetrical and reaching second pereiopod when abdomen flexed.

(See "Diagnosis" for description.)

SYNTYPIC FEMALE.—Differing from male, form I, in following respects: width of abdomen subequal to that of carapace (12.9 and 12.8 mm);

fovea on epistome not nearly so prominent; ratio of depth to width of chela 0.66; palm of chela less inflated, mesial surface with 7 tubercles in ventralmost row, 7 in middle, and 6 in dorsal (left

chela with 6, 7, and 5, respectively); fingers not conspicuously gaping; mesial surface of carpus with 3 tubercles proximal to major spine; dorsal surface of merus with 2 premarginal spiniform tubercles, ventrolateral row of tubercles represented by 1 well-developed spiniform tubercle and 2 or 3 vestigial ones, ventromesial row con- sisting of 10 (left with 12) subspiniform to spiniform tubercles. (See Table 1.)

Annulus ventralis (Figure Id) firmly, but not inflexibly, fused to sternum, subrectangular in outline and about 1.7 times as broad as long.

Cephalic half with median trough narrow and reaching submedian fossa slightly cephalic to level of maximum width; digitiform tongue arched caudosinistrally; sinus in form of tilted reversed S, its caudal extremity situated on mid- line of caudal wall. Postannular sclerite approximately 3 times as broad as long, about three- fourths width of annulus, and approximately two- fifths as long. First pleopod extending cephalically to midlength of annulus when abdomen flexed.

SYNTYPIC MALE, FORM II.—Differing from male, form I, in following respects: areola with punctations more sparsely distributed, 5 across narrowest part; antenna reaching tergum of fifth abdominal segment; palm of chela less inflated, ratio of depth to width 0.69; mesial surface of palm with 5 tubercles in ventralmost row, 7 in middle, and 6 in dorsal (left chela with 4, 7, and 5, respectively); fingers not conspicuously gaping;

hook on ischium of third pereiopod greatly reduced. (See Table 1.)

First pleopod (Figure \c,e) reaching coxa of second pereiopod, conspicuously less deeply cleft than in first form male, terminal elements shorter and more robust, and central projection less acute.

COLOR NOTES.—Based on specimen from a tributary to Cox Creek, Lauderdale County, Ala- bama. Basic coloration pale olive with brownish- olive and white to cream-olive markings. Dorsal part of cephalic region of carapace olive mottled with cream near apex of rostrum and with irregular brownish spots on most of rostrum and anterior gastric area; large oblique dark brown spots

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TABLE 1.—Measurements (in mm) of Orconectes alabamensis (Faxon)

Characters

Carapace Total length Postorbital length Height

Width Areola

Width Length Rostrum

Width Length Chela

Length of mesial margin of palm Width of palm Depth of palm Length of lateral

margin Length of dactyl Abdomen

Width Length

Syntypic male Form I

23.5 18.3 10.2 11.6 1.6 7.0 3.9 6.0 6.5 7.9 5.5 18.5 11.0 10.9 28.0

Syntypic female

26.1 19.9 11.1 12.8 1.4 6.9 4.4 7.6 5.5 6.5 4.3 15.8 9.4 12.9 30.4

Syntypic male Form II

19.4 14.5 9.1 9.7 1.5 5.3 3.3 5.5 3.6 4.2 2.9 11.5 6.9 8.6 22.1

overlying origins of mandibular adductor muscles joined by narrow posteromedian band; paired green markings flanking cephalic side of cervical groove largely separated from those over mandibular adductor muscles by 3 cream spots, paired elongate ones situated cephalolateral to caudomedian one. Postorbital ridges mostly pale olive but with brownish margins matching those on rostrum. Lateral surface of cephalic region pro- gressively paler ventrally, olive with irregular olive-tan markings, cephaloventral area cream to white. Thoracic section of carapace with conspicuous pair of large irregular splotches disposed subparallel to cervical groove and smaller pair abutting caudal margin of carapace, neither in- vading areola, latter pale olive with small brownish-olive splotches; lateral part of branchiostegites not covered by large splotches, fading ventrally to cream or white, and splotches becoming paler and more diffuse, disappearing along ventral margin. Abdominal terga pale olive mottled with darker olive and bearing paired brownish-olive splotches which viewed together constituting pair

of dorsolateral longitudinal stripes (splotches on anterior terga large but decreasing in size on more posterior ones, those on sixth very narrow and extending laterally, abutting proximal podomere of uropod). Row of brownish splotches present along bases of pleura. Telson olive with dark triangle anteriorly and with pair of dark spots at base of caudal section. Lateral borders of rami of uropods brownish but otherwise mostly pale olive mottled with small darker spots. Antennular and antennal peduncles pale olive mottled in cream and brownish splotches. Antennal scale with lateral thickened areas cream to white, lateral margin brown, and dorsal surface of lamellar area pale, mottled with brownish olive. Chelipeds olive mustard mottled with pale brown from midlength of merus to orange tips of fingers; more proximally, cream to white. Remaining pereio- pods mostly olive cream mottled with darker olive spots and splotches.

TYPE-LOCALITY.—Second Creek, Waterloo, Lauderdale County, Alabama.

TYPES.—Syntypes: National Museum of Nat-

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NUMBER 320

ural History, Smithsonian Institution, 4876 (146*1, 169, 46*11); Museum of Comparative Zoology, 3565 (26% 2$, 26*11).

RANGE AND SPECIMENS EXAMINED.—We have examined 443 specimens from northern tributaries of the Tennessee River from Shoal Creek in Lawrence County, Tennessee, and Lauderdale County, Alabama, westward through the latter and Wayne County, Tennessee, to the north-flowing segment of the river in Hardin County, Ten- nessee. This crayfish occurs on both sides of the divide between Cypress Creek and the Buffalo River in Wayne County, and is present in several localities in the headwaters of the latter stream.

It appears that the species is restricted to the Fort Payne chert formation which occurs on the north side of the Tennessee River.

VARIATIONS.—Perhaps correlated with the com- paratively small range of this crayfish, no clinal or locally restricted variations seem to exist.

Whereas the rostrum always bears a median carina, the margins may vary from subparallel to rather strongly convergent, and the marginal spines may be long and acute, short and rounded, or represented by very small tubercles. Likewise, there is considerable difference in the development of the cervical spines; nevertheless, in no specimens examined by us could they be termed vestigial. For ranges of variations in proportions, see "Diagnosis." The first pleopod of a single male from Buffler Spring in Lauderdale County, Alabama (Figure 2a) is markedly aberrant. (See last paragraph of "Variations" under Orconectes

validus.)

SIZE.—The largest specimen available is a female from the Cypress Creek watershed in Lau- derdale County, Alabama, possessing a carapace length of just under 35 (postorbital carapace length 27.1) mm. The corresponding lengths of the smallest first form male (a syntype) are 14.6 (11.3) mm; those of the largest male (Cypress Creek) are 33.0 (25.3) mm.

On the basis of collections at hand, some of the members of the species occurring in tributaries of Cypress Creek (Lauderdale County, Alabama, and Wayne County, Tennessee) attain a greater carapace length (often more than 30 mm) than

do those from Second Creek and adjacent tributaries to the Tennessee River (usually less than 25 mm).

LIFE HISTORY NOTES.—First form males were collected from October to April, and ovigerous females were found in February, March, and May. Of approximately 80 adult males collected from May to July, none was in the first form. No collections are available that were made in Au- gust or September. In October, of the 16 adult males, two were in the breeding form. Data on the ovigerous females are as follows:

Carapace length and (postorbital carapace length) (in mm)

28.3 (21.4) 26.2 (19.7) 22.1 (17.1) 21.1 (16.4) 17.1 (13.2)

Number

of'gg*

151 89 40 154 60

Diameter

ofeggs (in mm) 2.0-2.1 1.5-1.7 1.5-1.6 1.6-1.8 1.6-1.7

ECOLOGICAL NOTES.—Second Creek, the type- locality, at a road that joins County Roads 1 and

14, approximately 3 air miles (4.8 km) northeast of Waterloo (T IS, R 14W, Sec 20), is a clear, swiftly flowing stream with a rock littered bed, in some areas so swift as to be difficult to maintain a foothold. In such areas, Orconectes alabamensis was found along the lee sides of curves in littoral areas where leaves and debris had accumulated.

In two other localities in Lauderdale County, Alabama, this crayfish was found in dense mats of vegetation in spring runs.

In one locality on Buffalo Creek, Wayne County, Tennessee, the clear stream, some two to three meters wide and as much as 50 centimeters deep, flowed over bedrock with interspersed pools containing tree litter and a few rocks. There, all except one of the known crayfish associates, Cam-

barus (Hiaticambarus) sp., were collected with Or- conectes alabamensis in the pools.

RELATIONSHIPS.—See "Relationships" under Orconectes cooperi.

CRAYFISH ASSOCIATES.—Cambarus (Depressicam- barus) striatus Hay (1902:437), Cambarus {Hiaticam- barus) sp., Orconectes compressus (Faxon, 1884:127),

0.' forceps (Faxon, 1884:133), and 0. spinosus (Bundy, 1877:173).

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a

FIGURE 2.—Mesial view of atavistic (?) first pleopods of <3I:

a, Orconectes alabamensis from Buffler Spring on Mars Hill Road, 1.5 mi (2.3 km) NE of Coxes Creek Parkway, Florence, Lauderdalc County, Alabama; b, Orconectes valutas from a tributary to Brown's Creek, 2.5 mi (4 km) E of Arab on St Rte 69, Marshall County, Alabama.

Orconectes validus (Faxon)

FIGURES 26, 3-6

Cambarus immunis.—Hagen, 1870:73 [in part].

Cambarus validus Faxon, 1914:382, 383 [in part], 421, pi. VII:

figs. 4, 8; pi. XIII: fig. 1—Ortmann, 1931:91, 93, 94 [in part].—Hobbs, 1949:19.—Bouchard, 1976a:582.

Faxonius valtdus—Crcaser, 1933a:3 [by implication]; 1962:2 [by implication].

Faxonius (Faxonius) validus.—Creaser, 1933b:21 [by implica- tion].

Orconectts validus.—Hobbs, 1942a:352 [by implication]; 1949:

23; 1968:K14, K32, fig. 31f; 1972:90, 149, fig. 72b; 1974:

42, fig. 168.—Bouchard, 1976a:563, 574, 576, 582; 1976b:

14.—Bouchard and Bouchard, 1976:466,467, fig. 2c, d.—

Fitzpatrick, 1976:56.

Orconectes (Orconectes) validus.—Hobbs, 1942b: 154 [by impli- cation]; 1959:895.

DIAGNOSIS.—Body and eyes with pigment. Ros- trum lacking carina, usually with marginal tubercles, occasionally with distinct spines, and in- frequently tapering to apex without distinct angle at base of acumen. Areola obliterated (along part of length) to 7.4 times as long as wide and comprising 26.5 to 34.2 percent of entire length of carapace (36.3 to 43.9 percent of postorbital carapace length), with 0 to 2 punctations across narrowest part. Cervical spine present, sometimes reduced to tubercle. Suborbital angle obsolete.

Postorbital ridge well developed, with or without small apical tubercle. Antennal scale approximately 2.5 times as long as broad, widest at or slightly distal to midlength. Chela with palm inflated, bearing mesial row of about 8 subsqua- mous tubercles, and with irregular rows of tubercles subtending it; fingers gaping; fixed finger with proximal half of opposable margin studded with dense tufts of plumose setae. Hook on ischium of third pereiopod. First pleopod of first form male without angular shoulder on cephalic surface, with distal three-fifths inclined caudally;

terminal elements curved throughout and usually reaching base of second pereiopod when abdomen flexed; pleopod length divisible into carapace length 2.6 to 3.6 (average 3.2) times; terminal elements slender and subparallel: central projection, constituting 26.7 to 38.6 percent of total mesial length of appendage, bladelike, tapering from base and not extending so far caudally as mesial process; mesial process expanded distally and with shallow groove extending from near midlength of cephalic surface to caudally directed tip of process. Annulus ventralis as figured. First pleopod of female extending cephalically to midlength of annulus when abdomen flexed.

TOPOTYPIC MALE, FORM I.—Body and eyes pigmented. Cephalothorax (Figure 3a,i) subcylindrical in section; abdomen narrower than carapace (15.4 and 18.5 mm), width of latter greater than depth at caudodorsal margin of cervical groove (18.5 and 14.7 mm). Areola narrow, 27.8 times as long as wide with single punctation in

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NUMBER 320

narrowest part. Length of areola 31.8 percent of entire length of carapace (41.1 percent of postorbital carapace length). Rostrum with slightly thickened, elevated borders converging to base of acumen, and bearing corneous marginal tubercles; acumen reaching slightly beyond midlength of ultimate podomere of antennular peduncle and terminating in corneous, acute, upturned tip;

upper surface concave and punctate. Subrostral ridge weakly developed and evident in dorsal aspect only in caudalmost portion. Postorbital ridge strong, grooved laterally, and with sub- acute, corneous apical tubercle. Suborbital angle virtually obsolete. Cervical spine moderately heavy, short (left member bispinous), and only slightly larger than branchiostegal spine. Cara- pace punctate dorsally, punctations crowded and rather deep in cephalic gastric region; strongly granulate laterally except immediately ventral to cervical spines and near caudal extremity. Ab- domen and carapace subequal in length (35.2 and 34.9 mm). Pleura of moderate length, rounded ventrally. Cephalic section of telson with 2 spines in each caudolateral corner. Proximal podomere of uropod with short, corneous spine on each lobe; mesial ramus with moderately well- developed dorsomedian keel terminating in small premarginal spine.

Cephalic lobe of epistome (Figure 3g) distinctly broader than long with weak cephalomedian prominence and with cephalolateral borders un- dulating; main body of epistome with distinct fovea situated at cephalic end of median groove;

epistomal zygoma broadly arched. Basal segment of antennule with dense band of long plumose setae on mesial surface partially obscuring ventral spine located near midlength. Antennal peduncle with spine on lateral surface of basis and minute one on ischium. Antenna broken, but in other specimens reaching slightly beyond midlength of abdomen. Antennal scale (Figure 3/) about 2.4 times as long as broad, greatest width approximately at midlength; thickened lateral area with apical spine reaching level of tip of rostrum.

Third maxilliped with almost entire ventral surface of ischium and peduncle of exopodite bearing dense mat of plumose setae.

Chela (Figure 3;) about 2.3 times as long as wide; palm inflated, its mesial margin with mesial row of 8 tubercles, subtended dorsally and ventrally by irregular rows of 8 and 6, respectively;

remainder of palm punctate except for prominent tubercle ventrally opposite base of dactyl; lateral margin of chela subcostate almost from base to near midlength of finger, costa rounded laterally and polished. Fixed finger strongly arched laterally with opposable surface bearing, among setae, row of 11 tubercles along proximal three- fourths, fifth from base largest and all knoblike;

large tubercle at lower level between ninth and tenth tubercles from base; minute denticles extending distally from between seventh and eighth tubercles to corneous tip of finger; tubercles along proximal half of finger flanked by conspicuous tufts of plumose setae; dorsal and ventral surfaces of finger with broad, low submedian ridge flanked by setiferous punctations; secondary ridge present between median ridge and setal tufts. Dactyl with opposable margin concave basally and bearing row of 11 tubercles decreasing in size distally and extending along basal three-fourths of finger;

minute denticles extending from fifth tubercle from base to corneous tip of finger interrupted by more distal tubercles; dorsal and ventral surfaces of finger with low submedian longitudinal ridge flanked by setiferous punctations; secondary ridge situated between submedian ridge and opposable margin; mesial surface of dactyl tuberculate in proximal three-fourths and punctate distally.

Carpus 1.6 times as long as broad with deep oblique furrow on upper surface; mesial surface bearing prominent spine near midlength and 2 tubercles proximally; dorsal distomesial margin with low tubercle; ventrodistal margin with submedian corneous-tipped tubercle and another on ventrolateral condyle; ventromesial surface with 2 rounded tubercles.

Merus with 2 subdistal spines dorsally; mesial and lateral surfaces punctate; ventral surface with lateral row of 6 tubercles (third and sixth from base spikelike) and mesial row of 11, none of which spikelike; also lateral extremity with spine.

Ischium with row of 3 small tubercles, proximal- most largest.

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h

FIGURE 3.—Orconectes validus (topotypes, all from c5I except c, e from <5II, and d from $): a, lateral view of carapace; b, c, mesial view of first pleopod; d, annulus ventralis; e,f, lateral view of first pleopod; g, epistome; A, basis and ischium of third pereiopod; I, dorsal view of carapace; j , dorsal view of distal podomeres of cheliped; k, caudal view of first pleopods; /, antennal scale.

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NUMBER 320 11 Mesial surface of carpus and propodus of sec-

ond pereiopod not densely setose.

Ischium of third pereiopod with simple hook extending proximally over distal extremity of basis; hook not opposed by tubercle on basis.

First pleopods (Figures "ib^k) symmetrical, extending cephalically to second pereiopod when abdomen flexed. (See "Diagnosis" for description.)

TOPOTYPIC FEMALE.—Differing from male, form I, in following respects: abdomen and cephalothorax subequal in width (14.9 and 14.8 mm); areola only moderately narrow, 13.9 times as long as wide; marginal tubercles of rostrum minute; acumen reaching level of distal end of antennular peduncle; length of chela only 71 percent that of carapace, with inflation of palm and curvature of fixed finger less pronounced;

mesial margin of palm with mesial row of 9 tubercles subtended by irregular rows of 6 dorsally and 4 ventrally; fixed finger with 7 tubercles along proximal half of opposable margin, large one at lower level slightly distal to midlength,

and denticles beginning at midlength and extending almost to tip of finger; opposable margin of dactyl with 8 tubercles along proximal three- fifths; ridges on dorsal and ventral surfaces of fingers slightly stronger than in male; mesial surface of carpus with additional 3 small tubercles dorsal to those present on male. (See Table 2.)

Annulus ventralis (Figure 3d) moderately deeply embedded in sternum, firmly fused with latter cephalically; cephalic portion with antero- median trough flaring between and beneath oblique cephalolateral walls; digitiform tongue present, and wall of annulus caudal to tip of tongue strongly elevated and thickened; sinus originating under cephalosinistral wall slightly cephalic to midlength, following contour of tilted, reversed S, and ending on caudomedian wall of annulus. Postannular plate approximately 3 times as broad as long and about three-fourths width of annulus. First pleopod extending cephalically slightly beyond midlength of annulus when abdomen flexed.

TOPOTYPIC MALE, FORM II.—Differing from

TABLE 2.—Measurements (in mm) of Orconectes validus (Faxon)

Carapace Total length Postorbital length Width

Height Areola

Width Length Rostrum

Width Length Chela

Length of mesial margin of palm Width of palm Depth of palm Length of lateral

margin Length of dactyl Abdomen

Width Length

Topotypic male Form I

34.9 27.0 14.8 18.7 0.4 11.1 5.5 9.6 10.0 14.2 8.3 32.7 21.4 15.3 36.1

Topotypic female

30.0 22.9 12.8 14.8 0.7 9.7 4.6 7.9 7.1 8.6 5.5 21.4 12.5 15.1 32.4

Topotypic male Form II

30.4 23.1 12.5 15.2 0.6 9.7 4.9 8.2 6.5 9.5 6.0 23.4 15.0 13.5 31.3

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male, form I, in following respects: cephalic lobe of epistome trapezoidal with no cephalomedian projection; mesial margin of palm with mesial row of 8 tubercles, subtended by 7 dorsally and irregular row of about 4 ventrally; fixed finger with 14 tubercles along opposable margin, with 1 ventral to row; dactyl with 13 tubercles along opposable margin; hooks on ischia reduced and not overreaching distal extremity of basis. (See Table 2.)

First pleopod (Figure 3c,e) differing from that of first form male chiefly in decidedly shorter terminal elements, in the absence of corneous texture of central projection, in shallower cleft between elements, and in absence of groove on mesial process.

COLOR NOTES.—Based on specimens from Limestone County, Alabama. Cephalic part of carapace dark brown dorsally, fading ventrally but with irregular dark line extending caudally from level of antennal peduncle to cervical groove. Area over origins of mandibular adductor muscle with very dark brown reticulate pattern, and paired smaller, similarly dark patches along cervical groove immediately caudomesial to reticulate areas. Areola and branchiostegites mostly orange tan; dark brown saddle present caudally with horns produced cephaloventrally along ventral margin of carapace at least as far cephalically as level of cervical spine or tubercle. Basic color of abdomen dark brown; cephalic part of first abdominal tergum almost black, and caudal part as well as succeeding terga with paired dorsolateral dark brown splotches flanked laterally by 2 or 3 pale orange-tan spots at base of pleura.

Telson and uropods also dark brown, cephalic section of former with pale lateral areas. Anten- nular and antennal peduncles mottled, flagella orange tan to brown. Chelipeds mostly orange tan with dark markings on distal half of merus;

palm of chela with prominent black spot on dorsodistal condyle fading mesially along ridge flanking base of dactyl; lateral margin of propodus black, and both fingers with broad black transverse band between midlength and crimson to orange band on distal extremities; tubercles on cheliped pale orange to cream. Remaining per-

eiopods bearing brown bands on tan background.

Specimens from Hardin County, Tennessee, differing chiefly in possessing prominent dark splotches on cephalolateral parts of branchiostegites; caudal saddle on carapace not reaching ventral margin of branchiostegites; and dark oblique markings present along caudal margins of abdominal pleura. Some individuals with basic colors olive to gray, with dark gray to black markings.

TYPE-LOCALITY.—Huntsville (probably Hunts- ville Spring Branch within city limits), Madison County, Alabama.

TYPE.—Museum of Comparative Zoology, 301 (16*1). Topotypes, National Museum of Natural History, Smithsonian Institution, 132651 (56*1, 96*

II, 20$).

RANGE AND SPECIMENS EXAMINED.—We have examined approximately 900 specimens from the Tennessee River basin in Alabama and Tennessee and from the Black Warrior River system in Alabama. In the Tennessee Basin, Orconectes vali- dus ranges from the Paint Rock watershed in Jackson County, Alabama, downstream to Ben- ton County, Tennessee. Bouchard and Bouchard (1976:467) recorded "a single female from Mont- gomery County, Tennessee, (Cumberland River system) [which] may also be a member of this species possibly indicating a large range." In Al- abama, north of the Tennessee River, it is common in tributaries east of the Elk River, but few records of its occurrence downstream from the Elk watershed are available, and it has not been found within the range of O. alabamensis north of the Tennessee River (from Shoal Creek westward) . South of the Tennessee River proper, our collections indicate that it is common in Law- rence County and in the Bear Creek watershed in Colbert, Franklin, and Marion counties. Perhaps because of inadequate sampling, it is known from only a few localities in Marshall, Morgan, and Colbert counties. According to Bouchard (1976a:

576), writing of the crayfishes on the Cumberland Plateau, this crayfish "occurs in the sandstone and shale areas of the Plateau but is more common in limestone streams of the Highland Rim."

In the Black Warrior Basin, it is widespread in

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NUMBER 320 13

a d

f ^h\\/

FIGURE 4.—Antennal scales of Orconectes validus (a-g, Tennessee Basin; h, Black Warrior Basin):

a, Dry Creek, 2 mi (3.2 km) E of Monrovia, Madison County, Alabama; b, 3.6 mi (5.8 km) W of Athens, Limestone County, Alabama; c, 2.8 mi (4.5 km) NW of Brudy Lake, Lawrence County, Alabama; d, tributary to Bear Creek, 6.5 mi (10.4 km) S of Russellville on U.S. Hwy 43, Franklin County, Alabama; e, Bear Creek, 5.9 mi (9.4 km) S of Mackelberg on St Rte 5, Marion County, Alabama;/, 4.9 mi (7.8 km) N of Bath Springs at junction of St Rtes 69 and 114, Decatur County, Tennessee; g, Cypress Creek in Camden, Benton County, Tennessee; h, 15.7 mi (25.1 km) S of Double Springs on St Rte 195, Walker County, Alabama.

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the Sipsey Fork and other tributaries of the lower Mulberry Fork in Winston and Walker counties.

It occurs commonly in tributaries of the Locust Fork in Jefferson County and in those of the North River in Fayette County.

VARIATIONS.—On the basis of our specimens in the Black Warrior Basin this crayfish matures at a smaller size (carapace length less than 20 mm) but does not attain a carapace length as great as do those populations in the Tennessee drainage system (carapace length often greater than 30 mm). The relative degree of development of the marginal spines on the rostrum and cervical spines is quite variable: although in most populations the smaller individuals have more acute spines than do the larger ones, in some localities the spination, even in the adults, is markedly stronger than in individuals of comparable sizes in other populations. In some larger specimens, the spines on the rostrum are reduced to tubercles and the cervical spines are exceedingly small.

Occasional individuals have a low median carina on the rostrum, and the antennal scale is by no means uniform in outline (Figure 4).

In considering variations in the areolar width, the following arbitrary values have been used:

obliterated (Figure 5a,*/); narrow, more than 12 times as long as broad (Figure be); and wide, 12 or less times as long as broad (Figure 5 b,c,f).

While there is some variation in the relative width among individuals frequenting a single stream, greater differences occur between those occupying different streams. Within the range of the species, however, the extremes of variation are irregularly dispersed. In general, within the Tennessee Basin the areolae are narrow, except in two streams in Limestone County (Limestone and Round Island creeks) where they are obliterated, and in the following in which they are wide: tributaries to Bear Creek (Franklin and Marion counties), Wheeler Spring (Limestone County), some individuals in tributaries of the Flint River (Madison County), and most in Indian and Dry creeks (Madison County). In contrast, most of the ma- terial we have examined from the Black Warrior Basin possesses a wide areola; however, in several tributaries of Mulberry Fork, in the vicinity of

the Walker-Winston county line, the individuals are distinct from those elsewhere in the watershed in possessing an obliterated areola.

In comparing the length of the areola to that of the total length of the carapace, in the Ten- nessee Basin it constitutes 28.0 to 34.2 (average 30.9) percent for 112 specimens; in the Black Warrior, the corresponding range is 26.5 to 32.2

(average 29.7) percent for 48 specimens.

The ventral surface of the third maxilliped of specimens from the Bear Creek watershed (Ten- nessee Basin) in Franklin and Marion counties, Alabama, is not nearly so setose as that in specimens from other localities; the plumose setae on the lateral half of the ischium and on the merus are much shorter and far less conspicuous than in specimens from elsewhere in the range. In crayfish from the Black Warrior Basin, these plumose setae are more conspicuous than are those in the Bear Creek specimens, but the setae on the distal part of the lateral half of the ventral surface of the ischium are not nearly so long as those in specimens from elsewhere in the Tennessee Basin.

In collections from the North River watershed in the Black Warrior Basin, the fingers of the chela (Figure 6a) are proportionately longer than in most specimens from other localities. Varia- tions in configuration and setation of the chela in several populations are illustrated in Figure 6.

The ratio of the length of the central projection of the first pleopod to the mesial length of the latter varies from 26.7 to 38.6 (average 31.3) percent (Figure 5g-m). In the Tennessee Basin, the ratio ranges from 26.7 to 36.5 percent. In the Bear Creek watershed of this basin two specimens exhibit ratios of 32.5 and 36.5 (the latter occurring in the only specimen available from that watershed with a ratio greater than 35.4 percent).

In the Black Warrior Basin the ratio varies from 30.5 to 38.6 (average 34.4) percent.

A single first form male from the Tennessee Basin (small creek near Arab, Marshall County) bears a first pleopod with extremely short terminal elements (Figure 2b) unlike those in any known species. Repeated attempts by both of us independently to collect additional specimens have produced no more Orconectes from the same

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NUMBER 320 15

/ \

FIGURE 5.—Orcotuctes validus [a-f, areolae; g-m, mesial view of left first pleopod of 6*1; a-c, g-i from Black Warrior Basin; d-f, j-m from Tennessee Basin): a, Cane Creek, Walker County, Alabama; b, tributary to Mud Creek, Jefferson County, Alabama; c, tributary to Sipsey Fork, Winston County, Alabama; d, tributary to Round Island Creek, Limestone County, Alabama;

e, Cave Spring Cave, Morgan County, Alabama; / , The Dismals, Franklin County, Alabama;

g, same as b; h, North River, Fayette County, Alabama; i, same as a; j , Cypress Creek, Benton County, Tennessee (ml = mesial length); k, Fox Creek, Lawrence County, Alabama; /, same as d; m, same a s /

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FIGURE 6.—Chelae of 6*1 Orconectes validus (a-c, Black Warrior Basin; d-g, Tennessee- Basin): a, North River, Fayette County, Alabama; b, tributary to Mud Creek, Jefferson County, Alabama;

c, Cane Creek, Walker County, Alabama; d, Fox Creek, Lawrence County, Alabama; e, Cypress Creek, Benton County, Tennessee; / , The Dismals, Franklin County, Alabama; g, Bear Creek, Franklin County, Alabama.

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NUMBER 320 17 locality. Since the animal in all other respects

appears to be more similar to 0. validus than to any other species, and in view of the similar abnormally short pleopod found in a single specimen among a large series of the closely related O. alabamensis (Figure 2a), we tentatively assign this specimen to 0. validus, assuming a possible atavistic trait in its first pleopod.

SIZE.—The largest specimen available, a topotypic female, possesses a carapace length of 40.6 (postorbital carapace length 31.7) mm. The corresponding lengths of the smallest first form male are 18.8 (13.9) mm, and those of the largest, 38.6 (29.4) mm. The ranges of the corresponding lengths of the ovigerous females are 29.6 (22.0) to

19.5 (14.8) mm.

LIFE HISTORY NOTES.—First form males have been obtained during every month of the year except January and December, months during which none and only two adult specimens, respectively, have been collected. Fifteen ovigerous females and a single female carrying young were found in April. Data on 12 of the ovigerous females are as follows:

Carapace length and (postorbital carapace length) (in mm)

29.2 (21.7) 28.4 (20.9) 28.4 (21.8) 26.9 (20.7) 26.8 (19.9) 25.8 (19.3) 25.4 (19.8) 25.3 (19.6) 24.5 (18.5) 23.8 (18.4) 21.2 (15.7) 19.3 (14.8)

Number

of'gg*

158 183 180*

139*

69 128 206*

132*

179*

146*

100*

62*

Diameter

(in mm) 2.0-2.1 1.8-1.9 1.8-1.9 1.8-1.9 1.9-2.0 1.9-2.0 1.8-1.9 1.8-1.9 1.8-1.9 1.8-1.9 1.5-1.6 1.6-1.7

* These specimens were preserved in a single container in which an additional 49 eggs, lost by one or more of the specimens, were found on the bottom of the jar.

ECOLOGICAL NOTES.—Bouchard (1976a:582) noted that Orconectes validus occurs in "springs and small to medium sized streams under rocks, in leaf litter and in concentrations of aquatic vas- cular plants." Most of the collections examined by us have come from temporary and permanent streams with a rock-littered substrate. During dry

spells, some of the streams cease to flow, and the stream bed becomes dry except for occasional pools. In one stream bed in Madison County, there was no water on 23 September 1968, but a series of specimens was taken from beneath rocks.

In a stream 4.9 miles (7.8 km) west of Athens on U.S. Highway 72, the turbid water flows with a sluggish current over bedrock, gravel, and sand with few rocks in the stream bed. There this crayfish was collected among vegetation and from roots and debris along undercut banks of the stream.

RELATIONSHIPS.—See "Relationships" under

Orconectes cooperi.

CRAYFISH ASSOCIATES.—Collected with Orco- nectes validus in one or more localities were the following: Cambarus (Depressicambarus) obstipus Hall (1959:221), C. (/).) striatus, Cambarus (Hiaticamba- rus) sp., C. (Lacunicambarus) diogenes subsp., Falli- cambarus (Creaserinus) sp., Orconectes compressus, O.

cooperi, new species described herein, 0. erichsoni- anus, 0. etnieri, 0. forceps, 0. mints (Ortmann, 1931:

81), 0. perfectus Walls (1972:451), 0. spinosus, and Procambarus (Ortmannicus) acutus acutus (Girard,

1852:91).

Orconectes cooperi, new specks

FIGURE 7

DIAGNOSIS.—Body and eyes with pigment. Ros- trum with or without median carina, acumen delimited basally by marginal spines or tubercles.

Areola 4 to 6 times as long as wide and comprising 25.3 to 29.9 percent of total length of carapace (35.4 to 41.5 percent of postorbital carapace length). Cervical spine small; suborbital angle very weak to obsolete; postorbital ridges moderately well developed with small corneous tubercle cephalically. Antennal scale approximately 2.7 times as long as wide, broadest at about midlength. Chela of adult males conspicuously inflated, not costate laterally; tubercles on mesial margin of palm small and strongly depressed;

fingers gaping and conspicuous tuft of setae present along opposable basal part of fixed finger;

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opposable margin of dactyl not excised in basal third. Hook on ischium of third pereiopod of male. First pleopod of first form male (divisible into carapace length 2.9 to 3.2 times) reaching at least midlength of coxa of second pereiopod when abdomen flexed, without angular shoulder on cephalic surface; terminal elements subparallel and gently recurved along distal fifth; central projection constituting 35 to 38 percent of entire length of pleopod, bladelike and tapering from base to caudodistally directed apex; mesial process subcylindrical in section proximally, troughlike distally, its tip directed caudodistally not extending so far distad as central projection. An- nulus ventralis as figured. First pleopod present in female.

HOLOTYPIC MALE, FORM I.—Body and eyes pigmented. Cephalothorax (Figure la,i) subovate in section; abdomen narrower than carapace (15.6 and 13.3 mm), width of latter greater than depth at caudodorsal margin of cervical groove (15.6 and 14.8 mm). Areola moderately broad, 7.7 times as long as wide with 4 or 5 punctations across narrowest part; length of areola 28.9 percent of entire length of carapace (38.6 percent of postorbital length). Rostrum with margins little thickened, elevated, and bearing small marginal tubercles at base of acumen, latter reaching slightly beyond distal end of antennular peduncle; upper surface irregular with low median elevation distally and almost entirely punctate.

Subrostral ridge weak, disappearing completely in dorsal aspect before reaching midlength of rostrum. Postorbital ridge rather heavy with short dorsolateral groove and terminating cephalically in small, acute, corneous tubercle. Suborbital angle almost obsolete, delimited ventrally by shallow, broad, rounded notch. Cervical spine very small and acute. Carapace densely punctate dorsally and laterally, punctations deep and moderately large, and granulate ventrolaterally. Abdo- men longer than carapace (33.5 and 31.8 mm);

pleura well developed, subtruncate ventrally and subangular caudoventrally; cephalic section of telson with 2 spines in each caudolateral corner.

Proximal podomere of uropod with spine on each lobe, that on lateral lobe very small, both rami of

uropod with median keel ending in spine, that on mesial ramus premarginal.

Cephalic lobe of epistome (Figure 7^) with weak cephalomedian projection and irregular cephalolateral margins, latter elevated (ventrally), ventral surface with scattered setae; main body of epistome, set off from cephalic lobe by distinctly narrow base of latter, bearing deep cephalomedian fovea; epistomal zygoma broadly arched. Proximal segment of antennule provided with large spine near midlength, spine partly concealed by plumose setae extending from ventromesial margin of podomere. Antennal peduncle with small spines on basis and ischium, fla- gellum reaching tergum of fourth abdominal segment. Antennal scale (Figure 7i,/, latter from allotype) approximately 2.6 times as long as wide, broadest at midlength; thickened lateral area with apical spine reaching slightly beyond distal end of antennular peduncle. Ventral surface of ischium of third maxilliped with thick submar- ginal lateral row of long plumose setae, and surface between row and median ridge with several thick tufts proximally and scattered shorter ones distally, mesial half studded with dense mat of very long plumose and stiff hairlike setae; distolateral extremity of ischium with distinct corneous spine.

Right chela shorter than carapace (28.4 and 31.8 mm) (Figure 7/), about 2.2 times as long as wide with palm conspicuously inflated (ratio of depth to width 0.71), thickness subequal to length of areola and only slightly less than length of mesial margin of palm; latter with row of 7 very small squamous tubercles extending along proximal three-fourths, tubercles replaced distally by 2 conspicuous punctations; proximal part of row of tubercles flanked dorsolaterally by few additional smaller tubercles, palm otherwise punctate.

(Left chela with tubercle on ventral surface opposite base of dactyl.) Fingers gaping, with low submedian longitudinal ridges dorsally and ventrally; fixed finger with conspicuous mat of plumose setae at base and along proximal half of ventromesial surface of finger; opposable margin with row of 6 low, rounded corneous tubercles along basal three-fifths, and large one on lower

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NUMBER 320 19

FIGURE 7.—Orconecles cooperi (all from holotypic male, form I, except c, e, from morphotypic male, form II, and d, /, from allotype): a, lateral view of carapace; b, c, mesial view of first pleopod; d, annulus ventralis; e,f, lateral view of first pleopod; g, epistome; h, basis and ischium of third pereiopod; I, dorsal view of carapace; j , dorsal view of distal podomeres of cheliped; k, caudal view of first pleopods; /, antennal scale.

Crayfishes of the virilis Section of Genus Orconectes

New and Little-known